Last updated May 24, 2018 at 12:30 pm
We now have a better understanding of the population history of the Eurasian steppes after the Bronze Age migrations.
The analysis of dozens of ancient genomes is shedding new light on historical human migration patterns, as well as putting some competing theories about horse domestication and the spread of Indo-European languages under the microscope.
At the heart of the issue are the Botai, who lived on the Eurasian Steppe between 5150 and 3950 BCE and are regarded as the earliest known culture to have domesticated horses.
Some suggest the Botai were local hunter-gatherers who learnt horse husbandry from a western group of herders travelling eastbound; others suspect the domestication of horses arose locally within the Botai culture.
To explore this debate, an international research team analysed the genomes of 74 ancient humans who lived between 11,000 and 500 years ago in Eastern Europe, Central Asia, and Western Asia, and also examined genetic information from modern-day Asian populations.
They found little genetic mixing between groups closely related to Eastern European hunter-gathers and the Botai, suggesting that people likely migrated east through the Central Asian Steppe but did not settle until they reached the more eastern regions.
The authors say this means it is unlikely horse husbandry was brought to the Botai via western populations.
There is also debate about how and when genetic signatures and languages from western regions – specifically Indo-European languages – reached South Asia.
Based on their data, the researchers propose that two waves of genetic admixture occurred. The first came very early, potentially prior to the Bronze Age, and did not include Indo-European speakers, while the second came during the Late Bronze Age, bringing Indo-Iranian languages into South Asia.
The paper published in Science.